Electric motors can convert electrical energy into mechanical energy through electromagnetic interactions. The electric motors are widely used in daily life and applied to many fields. For example, the electric motors can be applied to machine tools, water pumps, light machineries, wind power systems, hydroelectric power generation systems and the like. The electric motors are fundamental machines in industry and closely linked with economic development.
In conventional electric motors, the motor performance can be improved by changing the material used in the electric motors, or adding more materials into the electric motors. For example, a synchronous electric motor is equipped with permanent magnets which are made of rare earth elements (REEs). However, since the energy saving issue is a matter of great concern for industries, the price of rare earth elements is getting higher, and related technologies are becoming more mature, the solution to reduce the usage of the rare earth elements as well as improve the motor performance has become one of the most important issues in the field of electric motor. As a result, a synchronous reluctant electric motor, without any rare-earth element permanent magnets, has become a new trend, but this type of motor has a disadvantage of requiring an actuator and a controller for operating smoothly.
Accordingly, an electric motor can become a very competitive electric motor if you simultaneously combine the high-performance feature of the synchronous reluctance electric motor, and the self-starting, high loading, high reliability features of the conventional asynchronous electric motor, which operates without the actuator, (a type of an induction motor).